The original circumferential routes were to improve north/south travel along 128.. then 495 to ease north/south travel without going through Boston (reducing traffic in the city). These loops did not add a huge increase in miles.. though with increase in population 495 has become just as jammed as the city. This loop is really out of the way.

until there is more work at either end (or along) that route, there really isn't a true need for it, as it creates a long route for little purpose (other than getting more people to the New Hampshire exit routes from Mass.. so no real need to go beyond 95 in the North.